Characterization of brown adipose tissue 18F-FDG uptake in PET/CT imaging and its influencing factors in the Chinese population

Abstract

18F-FDG PET/CT has been widely applied for tumor imaging. However, it is reported that many normal tissues, e.g., brown adipose tissue, can also uptake 18F-FDG. The purpose of this study was to determine the imaging characteristics of 18F-FDG uptake in brown adipose tissue (BAT) in PET/CT. A total of 2,944 patients who underwent PET/CT from September 2011 to March 2013 were analyzed retrospectively. Imaging features of 18F-FDG uptake in BAT were analyzed. Univariate analysis and logistic regression analysis were performed to evaluate the effect of age, gender, cancer status, body mass index (BMI), average daily maximum temperature of imaging month and fasting plasma glucose (Glu) on the positive rate of 18F-FDG uptake in BAT. The results showed that 1.9% (57/2944) patients had 18F-FDG uptake in BAT. 18F-FDG, manifested as flaky, nodular and beaded shape, was symmetrically distributed in the adipose tissues of cervical and supraclavicular, mediastinal, paravertebral, and perirenal areas. Uptake of 18F-FDG within cervical/supraclavicular area was most common (89.5%, 51/57) with an SUVmax ranging from 2.8 to 31.4. Univariate analysis showed that gender and cancer status were not significantly correlated with the BAT 18F-FDG uptake rate. In contrast, age, BMI, Glu and average daily maximum temperature in the imaging month were significantly correlated with the BAT 18F-FDG uptake rate (P<0.05). Further logistic regression analysis showed that only age, BMI and average daily maximum temperature were significant (OR<1, P<0.05). Based on the value of OR, the most significant factor that affects BAT 18F-FDG uptake rate was age, followed by the average daily maximum temperature and BMI. We concluded that Chinese adult has low positive rate of 18F-FDG uptake in BAT. Cervical/Supraclavicular is the most common area with BAT 18F-FDG uptake. Age, average daily maximum temperature and BMI are independent factors affecting 18F-FDG uptake.